Earlier this year, Montano was considering going back to school and at least temporarily hanging up her gloves. That changed when the UFC opted to open a 125-pound division, and assembled a cast of female flyweights for its TUF reality series.

Montano, who grew up on a Navajo reservation in Arizona, claimed the championship via scores of 50-45, 49-46 and 49-46. She did so against a late-replacement opponent in Modafferi, after Sijara Eubanks, her original opponent, was hospitalized this week during her weight cut.

"[Modafferi] has been an inspiration since before I was fighting," Montano said. "We were bunk mates on the show and I know how huge of a heart she has. I'm so happy.

"I knew she has comfort in the Octagon and I've seen her fight. I've sparred with her. I know how much fun this is for her. It's not technically a war for her, it's her playground."

Modafferi, who fights out of Las Vegas, offered no excuses for the loss -- despite taking the bout on short notice. The 35-year-old is considered a veteran in female mixed martial arts, and had prior UFC experience as a TUF cast member in 2013.

"Nicco's awesome. She's so talented, I can't say enough about her," Modafferi said. "I gave everything I had in this fight. I was in shape. I'm just going to keep going back to my gym and improving."

The fight became a war of attrition by about the second round, as both flyweights maintained a high pace on their feet.

According to Fightmetric, Montano out-landed Modafferi in total strikes 158-to-107. She was most successful when aggressive, putting Modafferi on her back leg with punching combinations and kicks. She bloodied Modafferi's nose in the fourth round and took top position during key moments.

Modafferi answered Montano's offensive, striking with jabs and right hands, and caused significant swelling under Montano's left eye.

In the last minute of the fight, Modafferi nearly locked in an armbar that would have resulted in the biggest win of her 14-year career. Her head fell back in despair, as Montano managed to slip out of the submission.

Montano, who trains out of FIT NHB in Albuquerque, New Mexico, is one of the most inexperienced champions in UFC history -- and admitted to ESPN earlier this week she initially felt guilty about her place on the show.

She has embraced the position now, and is facing tough competition ahead. Valentina Shevchenko, a former UFC bantamweight title challenger and seasoned professional kickboxer, is probably the No. 1 threat to Montano's reign at 125 pounds.